From 9924a92a8c217576bd2a2b1bbbb854462f1a00ae Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Fri, 8 Feb 2013 21:59:22 -0500 Subject: ext4: pass context information to jbd2__journal_start() So we can better understand what bits of ext4 are responsible for long-running jbd2 handles, use jbd2__journal_start() so we can pass context information for logging purposes. The recommended way for finding the longer-running handles is: T=/sys/kernel/debug/tracing EVENT=$T/events/jbd2/jbd2_handle_stats echo "interval > 5" > $EVENT/filter echo 1 > $EVENT/enable ./run-my-fs-benchmark cat $T/trace > /tmp/problem-handles This will list handles that were active for longer than 20ms. Having longer-running handles is bad, because a commit started at the wrong time could stall for those 20+ milliseconds, which could delay an fsync() or an O_SYNC operation. Here is an example line from the trace file describing a handle which lived on for 311 jiffies, or over 1.2 seconds: postmark-2917 [000] .... 196.435786: jbd2_handle_stats: dev 254,32 tid 570 type 2 line_no 2541 interval 311 sync 0 requested_blocks 1 dirtied_blocks 0 Signed-off-by: "Theodore Ts'o" --- fs/ext4/indirect.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'fs/ext4/indirect.c') diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c index 193281098fb6..c541ab8b64dd 100644 --- a/fs/ext4/indirect.c +++ b/fs/ext4/indirect.c @@ -791,7 +791,7 @@ ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb, if (final_size > inode->i_size) { /* Credits for sb + inode write */ - handle = ext4_journal_start(inode, 2); + handle = ext4_journal_start(inode, EXT4_HT_INODE, 2); if (IS_ERR(handle)) { ret = PTR_ERR(handle); goto out; @@ -851,7 +851,7 @@ locked: int err; /* Credits for sb + inode write */ - handle = ext4_journal_start(inode, 2); + handle = ext4_journal_start(inode, EXT4_HT_INODE, 2); if (IS_ERR(handle)) { /* This is really bad luck. We've written the data * but cannot extend i_size. Bail out and pretend @@ -950,7 +950,8 @@ static handle_t *start_transaction(struct inode *inode) { handle_t *result; - result = ext4_journal_start(inode, ext4_blocks_for_truncate(inode)); + result = ext4_journal_start(inode, EXT4_HT_TRUNCATE, + ext4_blocks_for_truncate(inode)); if (!IS_ERR(result)) return result; -- cgit v1.2.3-70-g09d2